U.S. patent number 6,365,869 [Application Number 09/636,784] was granted by the patent office on 2002-04-02 for apparatus for laser processing foil material.
This patent grant is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Xinbing Liu, Steven Sansone, Robert Swain.
United States Patent |
6,365,869 |
Swain , et al. |
April 2, 2002 |
Apparatus for laser processing foil material
Abstract
Apparatus for laser processing a foil material workpiece held to
a workpiece holder by a vacuum while being processed by a laser.
The foil material workpiece spans a recess in the workpiece holder
and is held flat and taut across the recess. With the open space
beneath the foil material workpiece defined by the recess, the
laser beam can pass completely through the foil material workpiece
to form a through hole or through cut in the foil material
workpiece without impinging on the workpiece holder.
Inventors: |
Swain; Robert (Maynard, MA),
Liu; Xinbing (Acton, MA), Sansone; Steven (Medway,
MA) |
Assignee: |
Matsushita Electric Industrial Co.,
Ltd. (Osaka, JP)
|
Family
ID: |
24553305 |
Appl.
No.: |
09/636,784 |
Filed: |
August 11, 2000 |
Current U.S.
Class: |
219/121.6 |
Current CPC
Class: |
B23K
26/702 (20151001); B23K 26/382 (20151001); B23K
26/40 (20130101); B23K 2103/50 (20180801); B23K
2103/42 (20180801) |
Current International
Class: |
B23K
26/00 (20060101); B23K 26/38 (20060101); B23K
26/42 (20060101); B23K 026/00 () |
Field of
Search: |
;219/121.6,121.63,121.67,121.7,121.82 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Heinrich; Samuel M.
Attorney, Agent or Firm: Ratner & Prestia
Claims
What is claimed:
1. Apparatus for laser processing a foil material workpiece
comprising:
a laser unit for developing a laser beam for processing a foil
material workpiece;
a workpiece holder:
(a) adapted to hold a foil material workpiece,
(b) disposed in the path of the laser beam, and
(c) having:
(1) a recess in a first face of said workpiece holder extending
into said workpiece holder from said first face thereof,
(2) a groove in said first face of said workpiece holder between
said recess and a sidewall at the periphery of said workpiece
holder, and
(3) a vacuum passage extending through said workpiece holder and
opening at a first end into said groove; and
means for applying a vacuum to a second end of said vacuum
passage.
2. Apparatus for laser processing a foil material workpiece
according to claim 1 wherein said second end of said vacuum passage
opens into said sidewall of said workpiece holder.
3. Apparatus for laser processing a foil material workpiece
according to claim 1 wherein said groove in said first face of said
workpiece holder is circular.
4. Apparatus for laser processing a foil material workpiece
according to claim 3 further including a second circular groove in
said first face of said workpiece holder between said recess in
said first face and said sidewall at the periphery of said
workpiece holder and into which said vacuum passage opens.
5. Apparatus for laser processing a foil material workpiece
according to claim 4 further including at least one further groove
connecting the groove and the second groove such that when vacuum
pressure is applied to one of the groove and the second groove it
is applied to the other one of the groove and the second groove at
least through the further groove.
6. Apparatus for laser processing a foil material workpiece
according to claim 1 wherein said recess in said first face of said
workpiece holder is a through hole that extends completely through
said workpiece holder.
7. Apparatus for laser processing a foil material workpiece
according to claim 1 wherein said recess in said first face of said
workpiece holder is a blind hole that extends partially through
said workpiece holder.
8. Apparatus for laser processing a foil material workpiece
according to claim 1 further including means for imparting relative
movement between said workpiece holder and said laser unit.
9. Apparatus for laser processing a foil material workpiece
according to claim 1 wherein said groove in said first face of said
workpiece holder is rectangular.
10. Apparatus for laser processing a foil material workpiece
according to claim 9 wherein said recess in said first face of said
workpiece holder is rectangular.
11. Apparatus for laser processing a foil material workpiece
according to claim 10, further including a second rectangular
groove in said first face of said workpiece holder between said
recess in said first face and said sidewall at the periphery of
said workpiece holder and into which said vacuum passage opens.
12. Apparatus for laser processing a foil material workpiece
according to claim 11 further including at least one further groove
connecting the groove and the second groove such that when vacuum
pressure is applied to one of the groove and the second groove it
is applied to the other one of the groove and the second groove at
least through the further groove.
13. A foil material workpiece holder having:
a planar surface;
a recess in said planar surface;
a groove in said planar surface between said recess and a sidewall
at the periphery of said workpiece holder; and
a vacuum passage extending through said workpiece holder and
opening at a first end into said groove.
14. A foil material workpiece holder according to claim 13 wherein
a second end of said vacuum passage opens into said sidewall at the
periphery of said workpiece holder.
15. A foil material workpiece holder according to claim 13 wherein
said groove in said planar surface of said workpiece holder is
circular.
16. A foil workpiece holder according to claim 15 further including
a second circular groove in said planar surface of said workpiece
holder between said recess and said sidewall at the periphery of
said workpiece holder and into which said vacuum passage opens.
17. A foil material workpiece holder according to claim 16 wherein
said recess in said in said planar surface of said workpiece holder
is a through hole that extends completely through said workpiece
holder.
18. A foil material workpiece holder according to claim 16 wherein
said recess in said planar surface of said workpiece holder is a
blind hole that extends partially through said workpiece holder.
Description
TECHNICAL FIELD
The present invention relates, in general, to laser machining and,
in particular, to an apparatus and method for processing foil
material with a laser.
BACKGROUND OF THE INVENTION
In laser drilling and cutting of foil-like materials, such as thin
metal foils and plastic foils, the surfaces of the materials that
are being processed should be flat and taut to provide a focal
plane or image plane for the laser beam. Because these materials
are light and flimsy, holding them properly can be difficult.
One way of holding these light and flimsy materials flat and taut
is by the application of a vacuum through holes in a bed or
workpiece holder on which these light and flimsy materials are
laid. Typically, these workpiece holders are solid and present a
planar surface onto which the foil material workpiece to be
machined is laid and the foil material workpiece is held in place
by the vacuum.
One common laser machining operation is drilling a blind hole in
the foil material workpiece (i.e., a hole that is not a through
hole that extends completely through the workpiece). For such laser
machining operations, where the laser beam does not pass completely
through the foil material workpiece, an arrangement that includes a
bed having a planar surface on which the foil material workpiece is
held is fine. If, however, a through hole or a through cut is to be
formed in the foil material workpiece, the laser beam must pass
completely through the foil material workpiece and can impinge on
the planar surface of the workpiece holder on which the foil
material workpiece is being held. When the laser beam impinges on
the planar surface of the workpiece holder, small crater-like
formations are developed. As a result, the surface on which the
foil material workpiece is being held is no longer planar and the
workpiece no longer is held flat against the workpiece holder
throughout the extent of the foil material workpiece.
SUMMARY OF THE INVENTION
Accordingly, apparatus for laser processing a foil material
workpiece, constructed in accordance with the present invention,
includes a laser unit for developing a laser beam for processing a
foil material workpiece. Also included in this apparatus is a
workpiece holder that is adapted to hold a foil material workpiece
and is disposed in the path of the laser beam. This workpiece
holder has a recess in a first face that extends into the workpiece
holder and a groove in the first face between the recess and a
sidewall at the periphery of the workpiece holder. The workpiece
holder also has a vacuum passage extending through the workpiece
holder and opening at a first end into the groove. Apparatus for
laser processing a foil material workpiece, constructed in
accordance with the present invention, further includes means for
applying a vacuum to a second end of the vacuum passage in the
workpiece holder.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is best understood from the following detailed
description when read in connection with the accompanying drawing.
It is emphasized that, according to common practice, the various
features of the drawing are not to scale. On the contrary, the
dimensions of the various features are arbitrarily expanded or
reduced for clarity. Included in the drawing are the following
figures:
FIG. 1 is a block diagram of a preferred embodiment of apparatus
for laser processing a foil material workpiece constructed in
accordance with the present invention.
FIG. 2A is a top view of a preferred embodiment of a workpiece
holder constructed in accordance with the present invention and
useful in the FIG. 1 apparatus.
FIG. 2B is a side view of the FIG. 2A workpiece holder.
FIG. 3 is a top view of another preferred embodiment of a workpiece
holder constructed in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, apparatus for laser processing a foil material
workpiece, constructed in accordance with the present invention,
includes a laser unit 10 for developing a laser beam for processing
a foil material workpiece. For the embodiment of the invention
being described, laser unit 10 includes a laser source 12 that
emits a beam that passes through a variable beam attenuator 14.
Following variable beam attenuator 14, the beam is weakly focused
by a lens 16 to illuminate a mask 18. Laser unit 10 further
includes lenses 20 and 22 that image open apertures of mask 18 on a
workpiece 24, namely a foil material. It will be understood that
laser unit can include a diffractive optical element instead of
mask 18.
Apparatus for laser processing a foil material workpiece,
constructed in accordance with the present invention, further
includes a workpiece holder 26 that is adapted to hold foil
material workpiece 24 on a planar first face 27 of the workpiece
holder. Workpiece holder 26 is disposed in the path of the laser
beam developed by laser unit 10. For the embodiment of the
invention illustrated by the drawings, workpiece holder 26 is
stepped with the smaller portion fitted within and held by a boss
28.
As shown in FIGS. 2A and 2B, workpiece holder 26 has a recess 29 in
first face 27 of the workpiece holder. Recess 29 extends into the
workpiece holder from first face 27.
In one embodiment of the present invention, recess 29 is a circular
through hole that extends completely through the workpiece holder
from first face 27 to a second face 31. In a second embodiment of
the present invention, recess 29 is a blind hole that extends
partially through workpiece holder 26 from first face 27. This is
represented by dashed line 32 in FIG. 2B. A vent passage 33 is
provided for pressure relief to equalize the pressure outside the
foil material workpiece being held by the workpiece holder and the
pressure inside the blind hole recess.
It is important that the laser beam not impinge upon workpiece
holder 26 and damage the workpiece holder during laser processing
of foil material workpiece 24 and, in the event that the laser beam
impinges on the workpiece holder during laser processing of the
foil material workpiece, the damage to the workpiece holder does
not extend to beyond planar first face 27 of the workpiece holder
which would result in the foil material workpiece no longer being
planar and the foil material workpiece no longer being held flat
throughout the extent of the foil material workpiece.
Workpiece holder 26 also has a groove 34 in first face 27 of the
workpiece holder between recess 29 and a sidewall 36 at the
periphery of the workpiece holder. For the embodiment of the
invention illustrated by FIG. 2A, groove 34 is circular in shape.
It is apparent that groove 34 can take other shapes, such as
elliptical, square, or rectangular.
As shown in FIGS. 2A and 2B, workpiece holder 26 has a second
circular groove 38 in first face 27 of the workpiece holder. Groove
38 also is located between recess 29 and sidewall 36 at the
periphery of workpiece holder 26 and can take other shapes.
Workpiece holder 26 also has a vacuum passage 40 extending through
the workpiece holder and opening at a first end into grooves 34 and
38 through openings 41 and 42, shown most clearly in FIG. 2A. A
second end of vacuum passage 40 opens into sidewall 36 at the
periphery of workpiece holder 26.
Apparatus for laser processing a foil material workpiece,
constructed in accordance with the present invention, further
includes means for applying a vacuum to the second end of vacuum
passage 40. As shown in FIG. 1, such means can include a vacuum
source 44, of conventional construction and operation, connected by
suitable means to workpiece holder 26 at the second end of vacuum
passage 40.
When a vacuum is applied from vacuum source 44 through vacuum
passage 40 and openings 41 and 42 to grooves 34 and 38, portions of
foil material workpiece 24 are pulled down into the grooves
uniformly creating an even tension over recess 29 in the workpiece
holder. The degree of tension is determined by the width of the
grooves and the amount of the vacuum pressure that is applied.
Having a single flat plane, the laser beam has the same focal
distance across the foil material workpiece for the laser
processing being performed and allows the same process performance
criteria across the foil material workpiece. Workpiece holder 26
secures the foil material workpiece to the workpiece holder in a
fashion that does not damage the foil material workpiece.
The workpiece holder 26 also includes optional grooves 43 that
connect the grooves 34 and 38. The grooves 43 allow airflow from
groove 34 or 38 to groove 38 or 34 and are implemented in the
workpiece holder 26 to allow the foil material to be held in place
even when one of the openings 41 and 42 is blocked. In this
instance, vacuum pressure from the unblocked opening is applied to
both grooves 34 and 38. One of the vacuum openings may be blocked,
for example, when the foil material is pulled into the opening by
the vacuum. To prevent the blocked vacuum opening from blocking the
optional groove 43, it is desirable for the groove 43 to intersect
the grooves 34 and 38 at locations other than those occupied by the
vacuum opening.
Apparatus for laser processing a foil material workpiece,
constructed in accordance with the present invention, preferably
includes means for imparting relative movement between workpiece
holder 26 and laser unit 10. Such means are represented in FIG. 1
by a motor 46 that, for the embodiment of the invention being
described, causes workpiece holder 26 to move as the foil material
workpiece is being processed by the laser unit. The present
invention can be arranged to create the desired relative movement
in three dimensions. It will be understood that the desired
relative movement can be created by moving laser unit 10 rather
than workpiece holder 26 or both the laser unit and the workpiece
holder can be moved rather than only one of the two.
FIG. 3 shows another embodiment of a workpiece holder constructed
in accordance with the present invention. This workpiece holder 50
has a rectangular recess 52 that can be a through hole or a blind
hole and a first rectangular groove 54 in a face 56 of the
workpiece holder between recess 52 and the sidewalls or periphery
of the workpiece holder. For the embodiment of the invention
illustrated by FIG. 3, groove 54 is rectangular in shape but can
take other shapes.
As shown in FIGS. 3, workpiece holder 50 has a second rectangular
groove 58 in face 56 of the workpiece holder. Groove 58 also is
located between recess 52 and the periphery of workpiece holder 50
and can take other shapes.
Workpiece holder 50 also has a vacuum passage (not shown) extending
through the workpiece holder and opening at a first end into
grooves 54 and 58 through openings 60 and 62. A second end of this
vacuum passage opens into a sidewall at the periphery of workpiece
holder 50. This alternate embodiment also includes optional grooves
61 that connect the grooves 54 and 58. As with the grooves 43,
described above, the grooves 54 and 58 allow vacuum pressure to be
applied to both of the grooves 54 and 58 even when one of the
openings 60 and 62 is blocked.
While in the foregoing there have been described preferred
embodiments of the present invention, it should be understood by
those skilled in the art that various modifications and changes can
be made without departing from the true spirit and scope of the
present invention.
* * * * *